Just how dangerous is the situation at Japan’s crippled Fukushima Daiichi nuclear plant? Very, according to U.S. Senator Ron Wyden, a senior member of the Senate’s energy committee who toured the plant earlier this month.

Another big earthquake or tsunami could send Fukushima Daiichi’s fragile reactor buildings tumbling down, resulting in “an even greater release of radiation than the initial accident,” Mr. Wyden warned in a Monday letter to Japanese Ambassador to the U.S. Ichiro Fujisaki.

In particular, Japan isn’t moving fast enough to remove dangerous nuclear-fuel rods from the reactors, and the U.S. should offer its help to speed things along, Mr. Wyden urged […]

Mr. Wyden points out, though, that the schedule allows up to ten years to get all the spent fuel in all the Fukushima reactor pools out — something he says is too risky.

“This schedule carries extraordinary and continuing risk if further severe seismic events were to occur,” he wrote in his letter to Ambassador Fujisaki. “The true earthquake risk for the site was seriously underestimated and remains unresolved.”